1. Field of the Invention
The present invention relates to a system for generating hole diameter information for a printed board or printed circuit board and the like. In particular, the present invention relates to a system for generating hole diameter information for a printed board and the like, which is capable of reading hole diameter information from a pattern figure corresponding to a pattern for a printed board.
2. Description of the Prior Art
Printed boards are now widely used in various products ranging from household electric and electronic appliances to computers.
On the printed boards used for these products, various wiring patterns are drawn, and electric and electronic components which are incorporated therein are connected through lead lines and a desired circuit is formed. In this instance, the lead lines are in many cases, inserted into holes or openings, provided in the printed board and connected to the wiring pattern on the printed board by soldering or the like.
The holes in which the lead lines are inserted have various diameters depending on the types or shapes of the electric and electronic components to be mounted therein. Generally, these holes are formed by an NC machine tool, and their holing positions, hole diameters, number of holes, etc., are prepared as NC tape information in the form of coordinate information; such information indicating numerical values of the diameters, and the like.
Each of the holing positions can be read from a pattern figure corresponding to a pattern on the printed board, for example, from a negative film of the pattern by using a hole position reading device. However, as regards the hole diameters which are usually about 0.8 to about 10 mm, when the diameters are directly read as numeric information, there is a possibility of an errogenous reading. For this reason, from the standpoint of reliability, rather than reading the hole diameters directly, or together with the reading of the hole diameters, in many cases, the hole diameters are set and the hole position, corresponding to the set hole diameters, are read individually to obtain the hole positions corresponding to the hole diameters.
Thus, where the holes are formed, depending on the individual hole diameters, a directive figure, which coincides with the pattern of the printed board is used. Marks are, then, provided which are respectively, different from one another, depending on the hole diameters, and are assigned in the directive figure. Holes corresponding to desired hole diameters are individually read by discriminating the hole diameters. Alternatively, hole diameters to be selected are discriminated by colors from other hole diameters, and holes corresponding to desired hole diameters are read individually.
Recently, however, as the number and kinds of holes in the printed board increase and as the electric and electronic components become smaller and more complicated, and are formed with higher density, the holes provided in the printed board have further increased in number and
density, and the different kinds of the holes have also increased. Thus, in such conventional systems described in the foregoing, there are drawbacks in that an error in the directive figure or display of the hole diameters and an erroneaous recognition, as well as an error in the read position tend to occur. Furthermore, a hole position reading procedure must be repeated for each kind of hole diameter. This results in problems of low working efficiency, and in addition thereto, of increased errors.
Prior art technical documents related to the present invention and known by the inventors of the present application include U.S. Pat. No. 3,293,439 which discloses a system for determining a holing position from coordinate information, and Japanese Patent Laid-Open (KOKAI) Publication No. 58-50408 (1983) disclosing a system for determining a holing position and a diameter thereof by detecting a color mark of a detection hole based on a difference in color sensitivity.
However, in the former, all the drawbacks in the conventional systems mentioned above are involved, and in the latter, the system is insufficient in its precision and reliability, and further the system is complicated and is economically inefficient.